本文選題：鋰離子電池 + 電解液　； 參考：《中國礦業(yè)大學(xué)》2014年碩士論文

【摘要】：鋰離子電池技術(shù)由于可作為電動(dòng)汽車的動(dòng)力電源而在近年來日益顯示其重要性。鋰離子電池在首次充放電過程中形成的固體電解質(zhì)相界面膜對(duì)電池的性能起到關(guān)鍵的影響作用。選擇合適的電解液成膜添加劑，促進(jìn)電極表面形成有利于電池性能提高的SEI膜是改善鋰離子電池最簡單、經(jīng)濟(jì)的手段之一。本文研究了碳酸鉀、碳酸鈉、氟化鋰等無機(jī)鹽作為鋰離子電池電解液成膜添加劑對(duì)石墨電極性能的影響，首次創(chuàng)新性地提出將維生素E用作電解液成膜添加劑，研究了石墨負(fù)極在含有不同添加劑電解液中的電化學(xué)性能，深入研究了石墨電極性能改善的機(jī)理。測試手段包括充放電測試、循環(huán)伏安法、電化學(xué)阻抗譜、掃描電子顯微鏡等，實(shí)驗(yàn)主要內(nèi)容和結(jié)論如下： （1）在1mol/L LiPF6-EC:DEC電解液中添加飽和K2CO3，運(yùn)用循環(huán)伏安法、充放電測試和電化學(xué)阻抗譜測試研究了K2CO3對(duì)電池性能的影響。通過掃描電鏡分析了添加K2CO3前后SEI膜形貌及組成的變化，結(jié)果表明兩種電解液中形成的SEI膜擁有不同的形貌，組分也發(fā)生一定程度的改變；CV結(jié)果顯示，K2CO3的加入可以有效抑制電解液溶劑EC的還原分解，，從而改善了石墨電極的電化學(xué)性能；EIS結(jié)果表明，加入K2CO3使得電極的整體阻抗和SEI膜阻抗都有所減小，有利于電池性能的提高。 （2）研究了碳酸鈉作為成膜添加劑對(duì)鋰離子電池石墨電極的影響。運(yùn)用掃描電子顯微鏡觀察了在未添加和添加了Na2CO3的電解液中石墨電極表面SEI膜形貌和結(jié)構(gòu)的變化；采用循環(huán)伏安法和電化學(xué)阻抗譜測試技術(shù)研究了Na2CO3對(duì)石墨電極電化學(xué)性能的影響。結(jié)果表明，在1mol/L LiPF6-EC:DEC電解液中添加飽和Na2CO3可以促進(jìn)形成更加光滑致密的SEI膜，增大電極反應(yīng)的可逆性，有效抑制電化學(xué)過程中電解液的還原分解，從而提高石墨電極的電化學(xué)循環(huán)性能。 （3）研究了1mol/L LiPF6-EC:DEC:DMC電解液中維生素E和LiF的加入對(duì)石墨電極表面SEI膜形貌、結(jié)構(gòu)和電化學(xué)性能的影響。SEM圖觀察結(jié)果表示，LiF和維生素E添加到電解液中，促進(jìn)了SEI膜的形成，改善了SEI膜結(jié)構(gòu)；充放電結(jié)果表明，該兩種添加劑均可以顯著提高石墨電極的首次充放電容量和庫倫效率；CV研究結(jié)果表明，電解液中添加3%維生素E和LiF能抑制首次循環(huán)過程中EC的第一步還原反應(yīng)，提高鋰離子嵌入脫出的可逆性，從而提高首次可逆容量，改善循環(huán)性能。
[Abstract]:Lithium - ion battery technology has become more and more important in recent years because of the power supply which can be used as an electric automobile . The solid electrolyte phase interface film formed during the first charge and discharge of lithium ion battery plays a key role in improving the performance of the lithium ion battery . It is first proposed to use the inorganic salt of potassium carbonate , sodium carbonate and lithium fluoride as the electrolyte forming additive to improve the performance of the graphite electrode . The mechanism of improving the performance of graphite electrode is studied . The test method includes the charge and discharge test , cyclic voltammetry , electrochemical impedance spectrum , scanning electron microscope , etc . The experimental results are as follows :

( 1 ) The effects of K _ 2CO _ 3 on the performance of the battery were studied by cyclic voltammetry , charge - discharge test and electrochemical impedance spectroscopy . The morphology and composition of the SEI films were investigated by SEM . The results showed that the SEI films formed in the two electrolytes had different morphology and the components were changed to some extent .
CV results show that the addition of co3 can effectively inhibit the reduction and decomposition of electrolyte solvent EC , thus improving the electrochemical performance of graphite electrode ;
EIS results show that the addition of co3 can decrease the overall impedance and SEI film impedance of the electrode , which is beneficial to the improvement of cell performance .

( 2 ) The effect of sodium carbonate as film - forming additive on graphite electrode of Li - ion battery was studied .
The effect of Na2CO3 on the electrochemical properties of graphite electrode was studied by cyclic voltammetry and electrochemical impedance spectroscopy . The results show that adding saturated Na2CO3 in 1 mol / L lip6 - EC : DEC electrolyte can promote the formation of more smooth and dense SEI film , increase the reversibility of electrode reaction , and effectively inhibit the reduction and decomposition of electrolyte in electrochemical process , so as to improve the electrochemical cycle performance of graphite electrode .

( 3 ) The effects of the addition of vitamin E and LiF on the morphology , structure and electrochemical properties of SEI film on the surface of graphite electrode were studied . The results showed that LiF and E were added to the electrolyte , which promoted the formation of SEI film and improved the structure of SEI film .
The charge - discharge results show that the first charge - discharge capacity and coulombic efficiency of graphite electrode can be obviously improved by the two kinds of additives .
CV results show that the addition of 3 % vitamin E and LiF in the electrolyte can inhibit the first reduction reaction of EC during the first cycle and improve the reversibility of lithium ion intercalation , so as to improve the first reversible capacity and improve the cycle performance .

【學(xué)位授予單位】：中國礦業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM912;U469.72

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